Bacillus　cereus　LY-1　is　isolated　from　Indonesian　oil　sand　with　oil-sand　oil　as　the　only　carbon　source,　and　the　surfactant　secreted　by　bacteria　is　identified　as　lipopeptides.　GC　and　GC-MS　were　used　to　study　diesel　oil　degradation　by　B.　cereus　LY-1.　GC-MS　and　the　improved　B-L　method　were　used　to　study　the　changes　in　oil-sand　oil　composition　and　structural　parameters　due　to　bacterial　degradation.　The　results　of　GC-MS　show　that　the　main　volatile　components　of　diesel　oil　are　C11-C14　at　40celcius,　and　B.　cereus　LY-1　has　higher　degradation　efficiency　for　saturated　alkanes　and　normal　alkanes　with　high　carbon　number　(C15-C24).　In　the　experiment　of　degrading　oil-sand　oil,　the　four　results　of　components　show　the　resin　in　the　treated　oil-sand　oil　is　reduced　from　60.41　+/-　1.03%　to　55.03　+/-　0.39%,　the　aromatic　fraction　increased　from　21.04　+/-　1.09%　to　23.42　+/-　0.7%,　and　the　saturated　hydrocarbon　fraction　increased　from　17.59　+/-　2.08%　to　21.55　+/-　0.44%.　The　results　of　GC-MS　show　that　after　B.　cereus　LY-1　treatment,　long-chain　saturated　alkanes,　aromatics,　and　complex　aromatics　can　be　utilized　by　B.　cereus　LY-1,　and　some　relatively　simple　complex　molecules　are　produced.　The　structure　of　oil-sand　oil　that　became　loose　further　illustrates　this.　The　oil　components　of　oil-sand　oil　are　converted　to　light　components,　and　B.　cereus　LY-1　has　the　ability　to　convert　complex　petroleum　hydrocarbons　into　relatively　simple　fatty　hydrocarbons.